Manipulation of in vitro ruminal fermentation and digestibility by dried rumen digesta

Abstract

This experiment was to investigate the effect of dried rumen digesta (DRD) levels on rumen kinetic gas production, rumen ammonia-nitrogen (NH3-N) and digestibility of nutrients by using in vitro gas production techniques. The experimental design was a completely randomized design (CRD) and the dietary treatments were DRD supplementation at 0, 4, 8, 12, 16 and 20mg with 0.5g of roughage and concentrate ratio at 70:30. The gas production was recorded at 0, 0.5, 1, 2, 4, 6, 8, 12, 18, 24, 48, 72 and 96h of incubation and was used for calculated of kinetics gas. The results revealed that crude protein, NDF and ADF in DRD were 19.4%, 42.4% and 20.9% of DM, respectively. The intercept value (a) for the different treatments representing gas production from soluble fractions, gas production from the insoluble fraction (b), potential extent of gas production (a+b) were not significantly different among treatments (P>0.05). However, gas production rate (c) and cumulative gas production (96h of incubation) were significantly different between the supplemented groups and control (P<0.05) and were highest when supplementation of DRD at 8mg and the values were 0.09ml/h and 132.5ml/0.5g substrate, respectively (P<0.05). NH3-N concentrations were linearly increased when increasing levels of DRD and were highest with DRD supplementation at 20mg (25.3mg%). Moreover, in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) were highest when 8mg of DRD was supplemented and the mean values were 63.8% and 65.2% DM, respectively. Based on this experiment, it could be concluded that supplementation of DRD at 8mg could improve rumen fermentation, in vitro kinetics gas, NH3-N concentration and digestibility.